This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-104804, filed on Apr. 8, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an apparatus and method for detecting the moving direction of a movable body such as a person or the like, and a program.
2. Description of the Related Art
For example, a navigation apparatus, which acquires the current position of a transport apparatus such as an automobile or the like, displays that current position on a map, and gives a route guidance from the current position to a destination on the map, uses GPS (Global Positioning System) to acquire the current position. In order to cope with a case wherein such an apparatus cannot receive a radio signal from an artificial satellite which is required for that apparatus to measure its position, e.g., a case wherein the transport apparatus is traveling through a tunnel or an urban area with many high-rise buildings, the apparatus comprises a velocity sensor used to detect the moving velocity of the transport apparatus, and a gyro sensor used to detect the moving direction of the movable body, and performs inertial navigation using information detected by these sensors, thus allowing navigation in such a place.
On the other hand, a measurement device that uses GPS has undergone size and weight reductions, and a navigation apparatus that a person can carry is commercially available.
When the navigation apparatus is set in a transport apparatus such as an automobile, the relationship between the travel direction of the transport apparatus and the direction of the navigation apparatus is basically specified in advance. However, when a person carries the navigation apparatus, how that person holds the apparatus is unknown. For this reason, it is difficult to estimate the travel direction of a walking carrier with reference to the direction of the navigation apparatus.
According to one aspect of the present invention, there is provided a moving direction detection apparatus which can be carried by a movable body, and comprises an acceleration detection unit which detects acceleration component of the movable body, a first correction unit which corrects a carrying direction of the moving direction detection apparatus with respect to the vertical direction based on the direction of the acceleration component detected by the acceleration detection unit, a second correction unit which corrects the carrying direction of the moving direction detection apparatus with respect to the horizontal direction based on a periodic up/down pattern of an absolute value of the acceleration component of the movable body which is detected by the acceleration detection unit, and a moving direction detection unit which detects a moving direction of the movable body in accordance with correction results of the first and second correction units.
According to one aspect of the present invention, there is provided a moving direction detection method for detecting a moving direction of a movable body, comprising an acceleration component acquisition step of acquiring information of an acceleration component in a vertical direction and an acceleration component in a horizontal direction in association with an acceleration of the movable body, which is produced upon motion of the movable body, at a predetermined time interval, a vertical acceleration extreme detection step of detecting a maximal value where a change over time in absolute value of the acceleration component in the vertical direction, acquired in the acceleration component acquisition step, turns from up to down, and a minimal value where a change over time in absolute value of the acceleration component in the vertical direction turns from down to up, a horizontal acceleration extreme detection step of detecting a maximal value where a change in absolute value of the acceleration component in the horizontal direction turns from up to down within a time period between detection times of the maximal and minimal values of the absolute value of the acceleration component in the vertical direction in the vertical direction extreme detection step, a horizontal acceleration direction detection step of detecting a direction of the acceleration component in the horizontal direction at a detection time of the maximal value of the absolute value of the acceleration component detected in the horizontal direction in the horizontal acceleration extreme detection step, and a moving direction detection step of detecting a moving direction of the movable body based on the direction of the acceleration component in the horizontal direction detected in the horizontal acceleration direction detection step.